1. Field of the Invention
The present invention relates to an optical waveguide device.
2. Description of the Background Art
Recently, communication using an optical fiber in which large-volume data can be transmitted at high speed has prevailed, and electric appliances (such as a personal computer, a television, a DVD and the like) used in such communication has been widely spread at home and the like. Thus, an optical waveguide device used at a connection part with an optical fiber, a light source, a light detecting element and the like is required to be inexpensive and suitable for mass-production.
The optical waveguide device is constituted by mounting an optical waveguide comprising a core and a clad on a substrate in which an optical fiber guide such as a V groove is formed. Conventionally, as a manufacturing method of the optical waveguide device which is inexpensive and suitable for mass-production, a method of duplicating the optical waveguide (or stamping method) has been well known. According to the duplication method, a transparent resin which will become a clad layer is pressed with a stamper to form a groove and cured and then the groove is filled with a transparent resin of a core material and pressed by a flat plate and the like to form a core of the optical waveguide.
According to this method, after many grooves of the optical waveguides are formed in a large-area clad layer at the same time, cores are formed in the grooves, and they are bonded to the substrate in which the optical fiber guides are formed and cut into a plurality of chips. As a result, many optical waveguide devices can be manufactured at one time.
However, even when the optical waveguide devices can be mass-produced, if it is complicated to adjust and fix a position to set another member such as an optical fiber to be connected to the core of the optical waveguide, final productive efficiency is not improved.
Thus, there is proposed a method of aligning a core end of the optical waveguide with the optical fiber correctly. FIG. 1 shows an exploded perspective view to explain a conventional optical waveguide device 1 integrated with an optical fiber guide.
The optical waveguide device 1 comprises a substrate 8 comprising optical fiber guides 4a to 4c on its surface, a first clad layer 2a formed on the substrate 8 and comprising a Y-shaped core 5 formed in a groove 3, a second clad layer 2b formed so as to cover the core 5 and an upper face of the first clad layer 2a, and a cover glass 6. The optical fiber guides 4a to 4c are grooves to position optical fibers 7a to 7c and have V-shaped section.
Here, the optical fibers 7a to 7c are fitted in the optical fiber guides 4a to 4c so that optical axes of the optical fibers 7a to 7c coincide with an optical axis of the core 5 as shown in FIG. 2A. In other words, they are arranged so that core end faces of the optical fibers 7a to 7c coincide with an end face of the core 5. In addition, the optical fibers 7a to 7c are fixed to the substrate 8 over almost entire lengths of the optical fiber guides 4a to 4c with an adhesive agent applied to a space between the optical fiber guides 4a to 4c and the optical fibers 7a to 7c. 
However, according to the optical waveguide device having the above constitution, the optical fibers 7a to 7c are positioned in a width direction of the optical waveguide device 1 by the optical fiber guides 4a to 4c but they are not positioned in a thickness direction. When the optical fibers 7a to 7c are fixed with the adhesive agent in this state, tip ends of the optical fibers 7a to 7c lift from the optical fiber guides 4a to 4c because of undulation of the optical fibers 7a to 7c caused by warp age of the optical fibers 7a to 7c themselves or hardening shrinkage of the adhesive agent in the length direction of the optical fibers 7a to 7c. As a result, as shown in FIGS. 2B and 2C, the optical fibers 7a to 7c are shifted upward at the time of bonding in some cases. In addition, when the tip ends of the optical fibers 7a to 7c lift, since they are separated from the optical fiber guides 4a to 4c, the optical fibers 7a to 7c are not positioned in the width direction of the optical waveguide device 1 also.
Thus, when the optical fibers 7a to 7c are shifted from the end faces of the core 5 of the optical waveguide, the optical axes of the optical fibers 7a to 7c are shifted from that of the core 5, so that insertion loss of light from the optical fibers 7a to 7c to the core 5, or from the core 5 to the optical fibers 7a to 7c deteriorates. Therefore, it is necessary to align the end face of the optical fiber and the end face of the core of the optical waveguide so as not to be shifted and to fix them with a cover from above.